This means that the visual has 8 planes, for a total of 256 colormap entries. Each colormap entry has a depth of 15 bits (5 bits per channel) for a total of 32,768 colors per colormap entry. The reason it's 5 bits per channel and not 8 is because the overlay hardware only supports depth 15.

Hi,
I'm also looking for a card that can support the full 8 bits in overlay mode. I've got a QUADRO FX 560 but it gives me only 5 significant bits per color. Which NVIDIA cards support the 8 bits/color in overlay mode?
thanks,